Multi-mode cone beam CT radiotherapy simulator and treatment machine with a flat panel imager

ABSTRACT

A multi-mode cone beam computed tomography radiotherapy simulator and treatment machine is disclosed. The radiotherapy simulator and treatment machine both include a rotatable gantry on which is positioned a cone-beam radiation source and a flat panel imager. The flat panel imager captures x-ray image data to generate cone-beam CT volumetric images used to generate a therapy patient position setup and a treatment plan.

TECHNICAL FIELD

The present invention pertains in general to therapeutic radiology. Inparticular, the invention involves imaging devices.

BACKGROUND

An objective of radiation therapy is to maximize the amount of radiationto a target volume (e.g., a cancerous tumor) and minimize the amount ofradiation to healthy tissues and critical structures. The process ofidentifying the precise location of the target volume immediately priorto a dose of therapeutic radiation is key to the objective. Since eachpatient is treated over 30 to 40 fractionated sessions, then the timeallowed for each session is relatively short, e.g. 10 to 15 minutes, sothe process must be fast as well as accurate.

In the case of electronic portal imaging, megavolt therapeutic X-raysemerging from the patient can be used to generate images. However, thismethod of target location generates images of low contrast and quality,in addition to incidentally damaging healthy tissue. As a result,imaging with megavoltage (MV) radiation is used primarily for portalverification, that is, to confirm that the treatment volume is beingradiated.

Radiotherapy simulator machines have been used to perform thepretreatment analysis of the target volume before a radiotherapytreatment machine applies the therapeutic radiation. However,traditional radiotherapy simulator machines use bulky image intensifiertube detectors to capture images of the treatment volume. These imageintensifier tube detectors have the disadvantage of being very largerelative to their imaging area. They also have image spatial distortionsfrom their spherical shaped input surface and the orientation of theintensifier tube with the Earth's magnetic field.

SUMMARY OF AN EMBODIMENT OF THE INVENTION

A multi-mode cone beam computed tomography radiotherapy simulator andtreatment machine is disclosed. The radiotherapy simulator and treatmentmachine both include a rotatable gantry on which is positioned acone-beam radiation source and a flat panel imager. The flat panelimager captures x-ray image data to generate cone-beam CT volumetricimages used to generate a therapy patient position setup and a treatmentplan.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

FIG. 1 is an illustration of a side view of one embodiment of asimulation treatment machine;

FIG. 2 is an illustration of a process flow of one embodiment of amethod for generating a treatment plan;

FIG. 3 is a side view of one embodiment of a clinical treatment machine;and

FIG. 4 illustrates a process flow of one embodiment of a method forimplementing a treatment plan.

DETAILED DESCRIPTION

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be evident, however, toone skilled in the art that the present invention may be practicedwithout these specific details. In some instances, well-known structuresand devices are shown in gross form rather than in detail in order toavoid obscuring the present invention. These embodiments are describedin sufficient detail to enable those skilled in the art to practice theinvention, and it is to be understood that other embodiments may beutilized and that logical, mechanical, electrical, and other changes maybe made without departing from the scope of the present invention.

A clinical therapy simulation machine having a cone-beam computedtomograpy (CT) radiation source and a flat-panel imager is described.The clinical therapy simulation machine is capable of manipulating theflat-panel imager and the cone beam CT radiation source to generatex-ray images for determining patient setup/alignment and a clinicaltreatment plan to be implemented by a clinical treatment machine.

FIG. 1 is a side view of one embodiment of a simulation treatmentmachine 100. The simulation treatment machine 100 includes a rotatablegantry 202 pivotably attached to a drive stand 203. A cone-beam CTradiation source 204 and a flat panel imager 206 oppose each other andare coupled to the rotatable gantry 202. In one embodiment, thecone-beam CT radiation source is a kilovoltage radiation sourcegenerally in the 50 to 150 kilovolt (kV) energy range, and for exampleat 125 kilovolts peak (kVp).

A treatment couch 218 is positioned adjacent to the gantry 202 to placethe patient and the target volume within the range of operation for theradiation source 204 and the imager 206. The couch 218 may be connectedto the therapy simulator rotatable gantry via a communications networkand is capable of translating in multiple planes plus angulation 219 forpositioning and re-positioning the patient 205 and therefore the targetvolume.

The gantry 202 can rotate 214 about an isocenterline 215 to place theradiation source 204 and imager 206 at any position 360 degrees aroundthe target volume, for example, to generate CT scan image data. As willbe described, cone-beam CT image data can be used to generate athree-dimensional representation of the patient anatomy and the targetvolume. The image data may further be used to generate a treatment planto tailor a dose of therapeutic radiation to the target volume.

FIG. 2 is a process diagram of one embodiment of a method for generatinga treatment plan. At block 310, a patient is placed on the treatmentcouch 218 and the couch 218 positioned relative to the simulationmachine 100. At block 320, the gantry 202 rotates around the patient 205while the radiation from the cone-beam CT radiation source 204 impingesthe flat-panel imager 206. The gantry 202 rotates and collects imagedata until a computer can calculate a representation of the patient andthe target volume. For example, software in a computer may take theimage data to generate cone-beam CT volumetric image data for generationof a treatment plan. At block 330, a treatment plan may be generatedfrom the collected image data. The treatment plan may then betransferred, at block 340, to a clinical treatment machine to provideinstructions to the clinical treatment machine, for example, to positiona therapeutic radiation source to apply a radiation dose to a targetvolume, and to minimize dose to health tissue and critical structures.

In one embodiment the flat panel imager 206 is a real-time digital x-rayimager incorporating a large-area amorphous silicon sensor array with ahigh-sensitivity cesium iodide (CsI) scintillator. The flat panel imagermay include a receptor module that incorporates the amorphous siliconsensor array, which accepts incoming X-ray photons and converts them toa digital video signal. The X-ray to light conversion may be provided bya thin or thick columnar CsI:Tl (cesium iodide: thalium doped)scintillator The scintillator may be vacuum deposited in a thin (e.g.0.6 mm) layer or include individual CsI crystals (e.g., beingapproximately 9 mm thick with an approximate 0.38 mm×0.38 mm pixelpitch) supported in a housing with an aluminum window (e.g.,approximately 1 mm thick). The top of the thin CsI scintillator may becoated with a reflective powder/epoxy mixture. Five sides of each thickcrystal may be coated with a reflecting powder/epoxy mixture. The sixthside may be in contact with and face the flat-panel sensor.Alternatively, the scintillator components may have other dimensions.

The receptor module may also include a power supply module (e.g., 24 VDCpower), interconnecting cables (e.g., fiber optic control and datacables), and drive and readout circuits followed by digital dataconversion and transmission capabilities well known to those of ordinaryskill in the art.

It should be appreciated that the flat panel imager may be atwo-dimensional large flat panel imager that can operate, for example,at 15 to 30 frames per second (fps) over a wide range of dose. In thisway, fluoroscopic, radiographic and cone-beam CT imaging can all beachieved with the same flat panel system. Typically, 300-900 projectionsmay be collected during a single rotation of the gantry depending on theimage resolution and dose requirements. Fewer projections allow for afaster collection of cone-beam CT image data (e.g., in 20 to 40 secondsdepending on gantry speed limits), thereby, allowing for lower dosecone-beam CT images with less patient motion artifacts. Alternatively,the images may operate at other frame rates.

In one embodiment, the flat panel imager has a landscape orientation, anactive area of 39.7×29.8 cm² with 194 micron pixel pitch, and a pixelcount of 2048×1536 pixels. It can operate at a frame rate of 7.5 fps infull resolution mode and at a frame rate of 30 fps in 2×2 binnedmode—where the pixel count is reduced to 1024×768 pixels². For example,the flat panel imager may be an amorphous silicon (a-Si) imageravailable from Varian Medical Systems of Palo Alto, Calif., under thetradename PaxScan™ 4030A. The PaxScan™ 4030A detectors are each 40 cm×30cm. The detectors may be coupled to signal processing circuitrycomprising a preamplifier stage with dynamically controllable signalgain, as described in U.S. Pat. No. 6,486,808, filed on Oct. 16, 2001,assigned to the assignee of the present invention and incorporated byreference, herein, to improve contrast resolution and dynamic range.

The readout electronics may also be located out of the path of theprimary cone-beam CT radiation source 204. The flat panel imager 206 mayalso employ a split data-line where the top half of the array and thebottom half of the array are read out simultaneously. This allows theimager 206 to read out more rapidly and reduces the parasiticcapacitance of the data-lines, which in turn reduces the noise gain ofthe readout charge amplifiers. It should be appreciated that only halfof the frame time is used to read out the pixels. During the rest of theframe time, the sensor can be irradiated without generating anyinterference patterns due to the pulsing of the cone-beam CT radiationsource 204. In addition, it should also be appreciated the controlsystem of the flat panel imager 206 allows an external synchronizationsignal (from the computer 220) to initiate the readout of a frame. Thisallows the user to externally control when the imager will acquire animage.

In one embodiment, a command processor module 225 manages the receptormodule, processes the digital video, and provides interfaces to othercomponents of the simulator 100. The command processor module 225 mayinclude a microcontroller-based, single board computer running areal-time operating system with acquisition, control, and interfacesoftware. Also, included in the command processor may be a high-speeddigital video interface card, a dedicated image processor card toperform real-time image corrections, a system interface card, and aparallel output to transmit image data to an external image processorand display. Scan-converted digital and analog video may also beprovided.

The captured cone-beam CT image projection data may be delivered andstored to a computer 220. As shown in FIG. 1, the computer 220 connectsto the simulator 100 and the command processor 225 via communicationsnetwork 240. The computer 220 may control the synchronized movement ofthe simulator 100 including the rotatable gantry 202, the cone-beam CTradiation source 204, imager 206, and the treatment couch 218.Specifically, the computer 220 may be used by an oncologist to displayimage projection data on a monitor 222, control the intensity of thecone-beam CT radiation source 204, and control the gantry angle.

The cone-beam CT image projection data may also be transferred to acone-beam CT reconstruction computer 221 that includes software designedto achieve rapid cone-beam CT image generation. The computer 221 canmerge or reconstruct the image data into a three-dimensionalrepresentation of the patient and target volume. In one embodiment,cone-beam CT reconstruction software may allow for full-cone andpartial-cone input data that can produce cone-beam CT images (e.g.,approximately 26 to 48 cm diameter) at a specific source-to-imagerdistance (e.g., 140-150 cm). In addition, in this way, the clinicalsimulator machine 100 and cone-beam reconstruction software may alsoallow for large diameter (e.g., approximately 48 cm) axial imagevolumes.

In one embodiment, the cone-beam CT reconstruction software maytransform the image projection data into volumetric CT image data. Thevolumetric CT image data may include full-fan and/or partial cone imagedata to reconstruct head size (e.g. 26 cm diameter×17 cm length) andbody size (e.g. 48 cm diameter×15 cm length) volumes. For example, thepartial-cone method may be used to obtain body size scans when the flatpanel imager is not long enough to image the full body in eachprojection. If the 15 or 17 cm axial section is not wide enough andtherefore does not cover sufficient anatomical volume, then multiplescans can be performed. For example, in the two scan case, the patientmay be moved axially by 15 or 17 cm couch movements between scans andthe reconstructed image volumes may then be merged to provide a 30 to 34cm axial view.

In one embodiment, prior to reconstruction, the image projection data ispreprocessed to account for x-ray beam and detector properties and thesystem electronic and geometric properties. The algorithm and itsimplementation is similar to that used in single slice computertomography in reconstruction of fan beam data obtained with aone-dimensional detector. For partial cone beam reconstruction, thepartial cone image projection data is extended to full cone beam imagedata and then reconstructed using a full cone beam reconstructionalgorithm well known to those of ordinarily skill in the art, such as,for example, the Feldkamp cone beam reconstruction technique. It shouldbe understood that the extension of the partial cone beam image data isperformed using techniques similar to those used for the extension ofpartial fan data in well known single slice fan beam computertomography.

In one embodiment, using the shape and distance data determined from thegenerated dimensional representation, the target volume may beautomatically identified by the computer system 221 and/or by theinspection of an oncologist. The identified target volume may be appliedto a radiotherapy planning computer system 220, which creates atreatment plan to be implemented by a clinical treatment machine. Thevisualization of the data along arbitrary planes, e.g. sagital, coronal,axial, beams eye view, etc., can be displayed to assist the oncologist.To further enhance the visualization, averaging of volume image dataperpendicular to the plane of view, i.e. rectangular voxels may be used.

FIG. 3 is a side view of one embodiment of a clinical treatment machine400 that may implement the treatment plan generated by the simulator 100and treatment planning computer 220. The clinical treatment machine 400includes a rotatable gantry 402 pivotably attached to a drive stand 403.A cone-beam CT radiation source 404 and a flat panel imager 406 opposeeach other and are coupled to the rotatable gantry 402. In oneembodiment, the cone-beam CT radiation source 404 is a megavoltage (MV)radiation source generally in the 4 to 25 MV energy range, for example,at 6 MV.

A treatment couch 418 is positioned adjacent to the gantry 402 to placethe patient and the target volume within the range of operation for theradiation source 404 and the imager 406. The couch 418 can be capable oftranslating in multiple planes plus angulation 419 for positioning andre-positioning the patient 405 and therefore the target volume.

The gantry 402 can rotate 414 about an isocenterline 415 to place thecone-beam CT radiation source 404 and imager 406 at any position 360degrees around the target volume. The resulting megavoltage cone-beam CTimage data can then be used to tailor a dose of therapeutic radiationbased on at least the generated pre-defined treatment plan.

FIG. 4 is a process diagram of one embodiment of a method forimplementing a treatment plan. At block 510, an accelerator controlcomputer 450 is provided with the treatment plan generated from theclinical simulator machine 100 for a specific patient. For example, thetreatment plan may provide initial targeting information about thetarget volume. At block 520, a patient is placed on the treatment couch418 and the couch 418 is positioned relative to the clinical treatmentmachine 400. At block 522, multi-mode cone beam radiation from theradiation source 404 is captured by the imager 406 to generate images ofthe target volume. At block 525, the captured image data can becompared/registered with the simulator or other reference images todetermine the patient repositioning required, if any, before treatment.Image data can also be taken without repositioning to determine therandom and systematic errors in treatment position, if any. At block530, the gantry 402 is rotated around the patient 405 to a treatmentposition based on the generated treatment plan. At block 540, atherapeutic radiation dose is applied to the target volume from thecone-beam CT radiation source 404 based on the generated treatment plan.The cone-beam CT radiation source 404 also impinges the flat-panelimager 406 with radiation. In this way, the flat panel imager 406 mayprovide verification that the target volume is properly targeted. Theprocess 500 may be repeated until the treatment session is complete.

The flat panel imager 406 is similar to the flat panel imager 206including the corresponding interconnects with a command processormodule 425, a computer 420, a monitor 422, and a cone-beamreconstruction computer 421, corresponding with the command processormodule 225, the computer 220, monitor 222, and the cone-beamreconstruction computer 221, as described above. However, in oneembodiment, the flat panel imager 406 may have its electronics unfoldedfrom beneath the imager 406 and the input screen coating may be thicker(e.g., 9 mm vs. 0.6 mm). An example of a flat panel imager that may beused in the present invention is described in U.S. patent Ser. No.10/013,199, filed on Nov. 2, 2001, now U.S. Pat. 6,800,898 B1 assignedto the assignee of the present invention and incorporated herein byreference.

The imager 406 may also interface with an accelerator interface controlbox 451. The accelerator interface control box 451 interfaces with anaccelerator control computer 450 to provide synchronization and gatedcontrol between the imager 406 and the cone-beam CT radiation source 404during treatment based on the generated treatment plan. As shown in FIG.3, box 451, processor 425, and computer 450 connect to simulator 400 viacommunications network 440. This allows single or multiple beam pulseimages that are not affected by accelerator noise during readout.

In one embodiment, the accelerator interface control box 451 includes atiming interface. The timing interface coordinates acquisition by theflat panel imager 406 and pulsing of the cone-beam CT radiation source404. With this interface, as little as one radiation pulse (0.028 cGy atthe isocenter) can be used to form projection images.

In one embodiment, the timing interface includes a National InstrumentsPCI 6602 data acquisition card from National Instruments Corporation ofAustin, Tex. USA, that contains hardware and firmware for counting andtiming pulses; computer software that provides control logic; and a userinterface for the interface system. Alternatively, other cards may alsobe used.

A master clock signal is derived from a sync signal of the cone-beam CTradiation source 404, which may operate at 360 pulses/s (6 MV) or 180pulses/s (15-18 MV), according to one embodiment. Using a counter on theNational Instruments PCI 6602 card, the sync signal is divided down toproduce a master clock, and hence are timed relative to the productionof cone-beam CT radiation pulses from the cone-beam CT radiation source404.

The master clock may be used to generate two control pulses, one thatgates the cone-beam CT radiation source 404 on and off and the otherthat triggers the flat panel imager 406. In one embodiment, thefrequency of these pulses is user selectable, and may be any value below30 pulses/sec. The relative timing of the two pulses may also be userselectable. When the flat panel imager 406 is triggered there is aperiod, while the image is being read out (half a frame time) duringwhich no beam from the cone-beam CT radiation source 404 is desired. Auser can enter the appropriate delay that will prevent irradiationduring the frame readout period of the imager. The length of the gatepulse of the cone-beam CT radiation source 404 is also user selectable.By adjusting the width of the gate pulse, the user can control thenumber of beam pulses emitted by the cone-beam CT radiation source 404during each gate pulse.

It should be appreciated that the MV cone-beam CT flat panel imager 406has a high quantum efficient 9 mm thick CsI:Tl screen (e.g.,approximately 10% efficient at 6 MV), which preserves spatial resolutionand minimizes dose to the patient by at least a factor of 5 over astandard 1 mm thin copper plate and less than 1 mm GOS (gadoliniumoxysulfide) screens used in standard flat panel and screen-camera portalimaging. Therefore, images with as low as one 6 MV accelerator beampulse (e.g., 0.028 cGy) per frame may be collected. In addition, a lowpatient dose of 8 to 16 cGy per cone-beam CT data set may be yielded for300 to 600 CT image frames or projections per data set. The lower doseof the MV cone-beam CT radiation allows for more frequent use on eachpatient during the typical 30 to 37 fractionated treatment sessions.Moreover, reduced spatial resolution on the MV cone-beam CT scans can beafforded for faster processing time using the cone-beam reconstructionsoftware on the CBR computer 421 to achieve rapid image generation.

It should be appreciated that a separate kV cone-beam CT radiationsource (optional and shown as source 430) and another opposing flatpanel imager (as described above on the simulator, optional and shown asimager 432) may also be coupled to the gantry 404 to perform adiagnostic cone-beam CT scan. For example, the kV cone-beam CT radiationsource and opposing flat panel imager may be coupled to the treatmentmachine gantry 404 at an off axis of e.g. forty-five or ninety degreesfrom the MV cone-beam radiation source 404 and opposing imager 406. Asbefore, software in the computers 420 and/or 421 may generate thethree-dimensional representation of the patient anatomy and targetvolume from the cone-beam CT image data provided by the kV radiationsource. The clinical treatment machine 400 may use the kV cone-beam CTimage data to make any necessary adjustments to the treatment plan basedon identified movement of the target volume or to determine the amountof patient repositioning required by the treatment couch 418 orcollimator movements. In this way, the kV cone-beam CT radiation sourceand flat panel imager share a common axis of rotation with the MVcone-beam CT radiation source 404 and provide additional information foraligning the patient to the generated simulation treatment plan.

It should also be appreciated that in this way, either the clinicalsimulator machine 100 and/or the clinical treatment machine 400diagnostic cone-beam CT image data can be used as a reference forapplying the MV radiation beams.

It should also be understood that it is not necessary for thetherapeutic radiation to be applied from the exact position(s) where anyof the previously generated CT images were taken since the computersoftware can provide virtual two-dimensional representations for anydesired radial location in-between the images.

It should be understood that although the clinical treatment machine 400has been described as having a cone-beam radiation source, inalternative embodiments beam shaping, along with intensity modulation,may also be implemented based on the generated treatment plan bydirecting a therapeutic beam through a dynamic multileaf collimator. Themultileaf collimator may include a series of stacked metal shims havinga center of shim pairs where each shim of the pairs may be individuallymoved to create a shaped opening capable of shaping the therapeuticbeam. To be effective, the radiation field should be large enough toradiate the entire tumor while at the same time minimize radiatinghealthy tissue. The collimator may be dynamic in that the shims canrapidly move to reshape the beam, which results in blocking thetherapeutic beam from striking certain areas of the target volume basedon the treatment plan. Such dynamic shaping may result in differentareas of the tumor receiving different amounts of radiation over thetime that a radiation dose is applied.

It should be appreciated that more or fewer processes may beincorporated into the methods illustrated in FIGS. 2 and 4 withoutdeparting from the scope of the invention and that no particular orderis implied by the arrangement of blocks shown and described herein. Itfurther will be appreciated that the method described in conjunctionwith FIGS. 2 and 4 may be embodied in machine-executable instructions(e.g. software). The instructions can be used to cause a general-purposeor special-purpose processor that is programmed with the instructions toperform the operations described. Alternatively, the operations might beperformed by specific hardware components that contain hardwired logicfor performing the operations, or by any combination of programmedcomputer components and custom hardware components. The methods may beprovided as a computer program product that may include amachine-readable medium having stored thereon instructions that may beused to program a computer (or other electronic devices) to perform themethods. For the purposes of this specification, the terms“machine-readable medium” shall be taken to include any medium that iscapable of storing or encoding a sequence of instructions for executionby the machine and that cause the machine to perform any one of themethodologies of the present invention. The term “machine-readablemedium” shall accordingly be taken to included, but not be limited to,solid-state memories, optical and magnetic disks, and carrier wavesignals. Furthermore, it is common in the art to speak of software, inone form or another (e.g., program, procedure, process, application,module, logic . . . ), as taking an action or causing a result. Suchexpressions are merely a shorthand way of saying that execution of thesoftware by a computer causes the processor of the computer to performan action or produce a result.

It should be appreciated that a clinical simulation machine having acone-beam radiation source and flat-panel imagers, as described, allowsfor identification of a target volume via fluoroscopic, radiographic,and cone-beam CT imaging. In this way, the generation of the treatmentplan via the clinical simulation machine prior to the application oftherapeutic radiation, increases the accuracy of treating the tumortarget. Furthermore, embodiments of the invention as described above maycapture images while the gantry is continuously rotating versustraditional systems that stop and shoot every, approximately, fourdegrees around the patient, thereby further lessening the time forcompletion.

It should also be appreciated that the cone-beam volumetricreconstruction software can utilize image projection data atnon-uniformly spaced gantry angles. Thus the data collection does notrequire a precise gantry speed of rotation. There is a normalizingdetector at the radiation source, which is used to correct for systemoutput variations. In one embodiment, the support arms for the images206 and 406 are sufficiently precise in mechanical stability duringgantry rotation that no compensating spatial corrections are required.

Although the present invention has been described with reference tospecific exemplary embodiments, it will be evident that variousmodifications and changes may be made to these embodiments withoutdeparting from the broader scope of the invention as set forth in theclaims. Accordingly, the specification and drawings are to be regardedin an illustrative rather than a restrictive sense.

1. An apparatus, comprising: a radiation treatment system capable ofimplementing a treatment plan, the system comprising: a frame; arotatable gantry coupled to the frame; a high-energy radiation sourcecoupled to the rotatable gantry to radiate a patient with therapeuticradiation; a cone-beam radiation source coupled to the rotatable gantryto radiate the patient; a flat-panel imager coupled to the rotatablegantry, wherein the flat-panel imager is operable to capture imageprojection data of the patient from the cone-beam radiation source togenerate cone-beam computed tomography (CT) volumetric image data of thepatient; and a computing unit, coupled to the rotatable gantry via acommunications network, to store the image projection data captured bythe flat-panel imager.
 2. The apparatus of claim 1, wherein theflat-panel imager is capable of fluoroscopic imaging, radiographicimaging, and cone-beam CT imaging.
 3. The apparatus of claim 1, whereinthe computing unit generates a treatment plan based on the imageprojection data.
 4. The apparatus of claim 1, wherein the computing unitgenerates a three-dimensional image of a target volume based on thecaptured image projection data.
 5. The apparatus of claim 1, wherein thecone-beam CT radiation source is a kilovoltage radiation source and thehigh-energy radiation source is a megavoltage radiation source.
 6. Theapparatus of claim 1, wherein the rotatable gantry is capable of 360degree rotation.
 7. The apparatus of claim 1, wherein the high-energysource comprises a megavoltage radiation source to radiate a targetvolume with radiation.
 8. The apparatus of claim 1, wherein the framecomprises a drive stand pivotably coupled to the rotatable gantry at apivotable attachment at which the gantry pivots about an isocenter. 9.The apparatus of claim 1, wherein the cone-beam source and high-energyradiation source are different from one another, and the cone-beamsource comprises a KV source and wherein the high-energy radiationsource comprises a MV source coupled to the rotatable gantry to radiatea patient with therapeutic radiation.
 10. The apparatus of claim 1,wherein the rotatable gantry is coupled to the frame at a rotationalaxis of the gantry; wherein the cone-beam radiation source is acone-beam imaging source coupled to a first end of a first arm, thefirst arm having a second end coupled to the gantry; wherein theflat-panel imager is coupled to a first end of a second arm, the secondarm having a second end coupled to the gantry; and wherein thehigh-energy radiation source comprises a high-energy cone-beam source.11. An apparatus, comprising: a radiation treatment system capable ofimplementing a treatment plan, the system comprising: a frame; arotatable gantry coupled to the frame; a high-energy radiation sourcecoupled to the rotatable gantry to radiate a patient with therapeuticradiation; a cone-beam radiation source coupled to the rotatable gantryto radiate the patient; and a flat-panel imager coupled to the rotatablegantry, wherein the flat-panel imager is operable to capture imageprojection data of the patient from the cone-beam radiation source togenerate cone-beam computed tomography (CT) volumetric image data of thepatient, wherein the flat-panel imager includes an amorphous siliconsensor array, and wherein the flat-panel imager includes a cesium iodidescintillator for kilovoltage imaging.
 12. The apparatus of claim 11,wherein the scintillator includes cesium iodide crystals coated with areflective powder and epoxy mixture in a large matrix for megavoltageimaging.
 13. An apparatus, comprising: a radiation treatment systemcapable of implementing a treatment plan, the system comprising: aframe; a rotatable gantry coupled to the frame; a high-energy radiationsource coupled to the rotatable gantry to radiate a patient withtherapeutic radiation; a cone-beam radiation source coupled to therotatable gantry to radiate the patient; and a flat-panel imager coupledto the rotatable gantry, wherein the flat-panel imager is operable tocapture image projection data of the patient from the cone-beamradiation source to generate cone-beam computed tomography (CT)volumetric image data of the patient, wherein the flat-panel imager iscapable of generating image projection data at 15 to 30 frames persecond.
 14. An apparatus, comprising: a radiation treatment systemcapable of implementing a treatment plan, the system comprising: aframe; a rotatable gantry coupled to the frame; a high-energy radiationsource coupled to the rotatable gantry to radiate a patient withtherapeutic radiation; a cone-beam radiation source coupled to therotatable gantry to radiate the patient; a flat-panel imager coupled tothe rotatable gantry, wherein the flat-panel imager is operable tocapture image projection data of the patient from the cone-beamradiation source to generate cone-beam computed tomography (CT)volumetric image data of the patient; and a translatable treatment couchcoupled to the rotatable gantry via a communications network.
 15. Theapparatus of claim 14, wherein the translatable treatment couch iscapable of movement in three planes plus angulation.
 16. An apparatus,comprising: a radiation treatment system capable of implementing atreatment plan, the system comprising: a frame; a rotatable gantrycoupled to the frame; a high-energy radiation source coupled to therotatable gantry to radiate a patient with therapeutic radiation; acone-beam radiation source coupled to the rotatable gantry to radiatethe patient; a flat-panel imager coupled to the rotatable gantry,wherein the flat-panel imager is operable to capture image projectiondata of the patient from the cone-beam radiation source to generatecone-beam computed tomography (CT) volumetric image data of the patient,wherein the a flat-panel imager is a flat-panel KV imager; and aflat-panel MV portal imager coupled to the rotatable gantry, wherein theMV imager is operable to capture image projection data of the patientproduced by the high-energy MV radiation source.
 17. A method to performa clinical treatment, comprising: rotating a gantry pivotably coupled ata pivot point to a frame of a clinical radiation treatment machinecapable of implementing a treatment plan; irradiating a patient with aradiation source; using the clinical radiation treatment machine tocapture image projection data from a flat-panel imager for generatingcone-beam computed tomography (CT) volumetric image data; and modifyinga treatment plan for the clinical treatment machine based on thecone-beam volumetric image data.
 18. The method of claim 17, furthercomprising: generating a treatment plan for the clinical treatmentmachine based on the cone-beam volumetric image data; and transferringthe treatment plan to the clinical treatment machine, wherein theclinical treatment machine implements the treatment plan.
 19. The methodof claim 17, wherein the radiation source is a cone-beam computedtomography radiation source, and wherein the image projection data isgenerated from a flat-panel imager capturing radiation from thecone-beam computed tomography radiation source passing through a targetvolume.
 20. The method of claim 19, wherein the radiation source is akilovoltage radiation source.
 21. The method of claim 17, wherein theimage projection data is fluoroscopic image projection data.
 22. Themethod of claim 17, further comprising: generating a treatment plan forthe clinical treatment machine based on the cone-beam volumetric imagedata; and using the treatment plan to instruct the clinical treatmentmachine to at least adjust a therapeutic radiation source into positionto align a treatment volume with the therapeutic radiation.
 23. Themethod of claim 17, further comprising: generating a treatment plan forthe clinical treatment machine based on the cone-beam volumetric imagedata.
 24. The method of claim 17, further comprising: positioning apatient based on the cone-beam volumetric image data.
 25. The method ofclaim 17, wherein the clinical radiation treatment machine comprises adrive stand pivotably coupled to the rotatable gantry at a pivotableattachment at which the gantry pivots about an isocenter.
 26. A methodto perform a clinical treatment, comprising: rotating a gantry pivotablycoupled at a pivot point to a frame of a clinical radiation treatmentmachine capable of implementing a treatment plan; irradiating a patientwith a radiation source; and capturing image projection data from aflat-panel imager using the clinical radiation treatment machine, theimage projection data for generating cone-beam computed tomography (CT)volumetric image data, wherein capturing comprises capturing the imageprojection data at a frame rate in the range of 15-30 frames per second.27. A method to perform a clinical treatment, comprising: rotating agantry pivotably coupled at a pivot point to a frame of a clinicalradiation treatment machine capable of implementing a treatment plan;irradiating a patient with a radiation source; using the clinicalradiation treatment machine to capture image projection data from aflat-panel imager for generating cone-beam computed tomography (CT)volumetric image data, wherein the radiation source is a cone-beamcomputed tomography radiation source, wherein the image projection datais generated from a flat-panel imager capturing radiation from thecone-beam computed tomography radiation source passing through a targetvolume; deriving a master clock signal from a synchronization signal ofthe radiation source; using the master clock signal to generate a firstcontrol pulse to gate the radiation source on and off and a secondcontrol pulse to trigger reading of an image from the imager; andselecting a timing of the first control pulse as compared to the secondcontrol pulse to read out the image while the radiation source is off.28. A method to perform a clinical treatment, comprising: rotating agantry pivotably coupled at a pivot point to a frame of a clinicalradiation treatment machine capable of implementing a treatment plan;irradiating a patient with a radiation source; using the clinicalradiation treatment machine to capture image projection data from aflat-panel imager for generating cone-beam computed tomography (CT)volumetric image data, wherein the radiation source is a cone-beamcomputed tomography radiation source, wherein the image projection datais generated from a tlat-panel imager capturing radiation from thecone-beam computed tomography radiation source passing through a targetvolume; continuously rotating the radiation source about the targetvolume while capturing image projection data; and one of capturing imageprojection data at non-uniformly spaced angles with respect to therotation, and changing the speed of rotation of the gantry during arotation.
 29. A method to perform a clinical treatment, comprising:rotating a gantry pivotably coupled at a pivot point to a frame of aclinical radiation treatment machine capable of implementing a treatmentplan; irradiating a patient with a radiation source; using the clinicalradiation treatment machine to capture image projection data from aflat-panel imager for generating cone-beam computed tomography (CT)volumetric image data, wherein the radiation source is a cone-beamcomputed tomography radiation source, wherein the image projection datais generated from a flat-panel imager capturing radiation from thecone-beam computed tomography radiation source passing through a targetvolume; and continuously rotating the radiation source about the targetvolume while capturing image projection data.
 30. An apparatus,comprising: one of a radiation simulation system comprising logicconfigured to determine a patient position relative to a high-energyradiation treatment beam and a radiation treatment system comprisinglogic configured to implement a treatment plan for a high-energyradiation treatment, the logic comprising at least one of hardwiredlogic and a programmable computer component, the system comprising: aframe; a rotatable gantry pivotably coupled to the frame at a pivotpoint; means for applying a cone-beam computed tomography (CT) radiationbeam coupled to the rotatable gantry; and means for capturing imageprojection data with a flat-panel imager, coupled to the rotatablegantry, to generate cone-beam computed tomography (CT) volumetric imagedata of a patient's anatomy.
 31. The apparatus of claim 30, wherein themeans for capturing includes an amorphous silicon sensor array.
 32. Theapparatus of claim 31, wherein the means for capturing includes a cesiumiodide scintillator for kilovoltage imaging.
 33. The apparatus of claim32, wherein the scintillator includes cesium iodide crystals coated witha reflective powder and epoxy mixture in a large matrix.
 34. Theapparatus of claim 30, wherein the means for capturing is capable offluoroscopic imaging, radiographic imaging, and cone-beam CT imaging.35. The apparatus of claim 30, wherein the means for capturing capturesthe image data at 15 to 30 frames per second.
 36. The apparatus of claim30, further comprising: means for storing the captured image projectiondata is coupled to the rotatable gantry via a communications network.37. The apparatus of claim 30, further comprising: means for generatinga treatment plan based on the image projection data coupled to the meansfor capturing via a communications network.
 38. The apparatus of claim37, wherein the means for generating generates a three-dimensional ageof a target volume based on the captured image projection data.
 39. Theapparatus of claim 30, wherein the means for applying includes akilovoltage radiation source.
 40. The apparatus of claim 30, furthercomprising a translatable treatment couch coupled to the rotatablegantry via a communications network.
 41. The apparatus of claim 40,wherein the translatable treatment couch is capable of movement in threeplanes plus angulation.
 42. The apparatus of claim 30, wherein therotatable gantry is capable of 360-degree rotation.
 43. The apparatus ofclaim 30, further comprising: means for generating a treatment plan fora clinical treatment machine based on the cone-beam volumetric imagedata; and means for treating a patient according to the treatment planincluding providing synchronization and gate control between the imagerand the radiation beam during treatment.
 44. The apparatus of claim 43,wherein treating includes means for coordinating acquisition by the flatpanel imager and pulsing by the radiation source.
 45. The apparatus ofclaim
 30. wherein the radiation simulation system comprises logicconfigured to determine a patient position relative to a high-energyradiation treatment beam of a treatment machine to be simulated by thesimulation system, the logic comprising at least one of hardwired logicand a programmable computer component; and wherein the radiationtreatment system includes a high-energy radiation treatment beam source.46. A machine-readable medium selected from the group consisting ofsolid-state memories, optical disks, and magnetic disks; themachine-readable medium having instructions to cause a machine toperform a method to perform a clinical treatment, the method comprising:rotating a gantry pivotably coupled at a pivot point to a frame of aclinical radiation treatment machine capable of implementing a treatmentplan; irradiating a patient with a radiation source; and instructing theclinical radiation treatment machine to capture image projection datafrom a flat-panel imager for generating cone-beam computed tomography(CT) volumetric image data.
 47. The machine-readable medium of claim 46,further comprising: generating a treatment plan for the clinicaltreatment machine based on the cone-beam volumetric image data; andtransferring the treatment plan to the clinical treatment machine,wherein the clinical treatment machine implements the treatment plan.48. The machine-readable medium of claim 46, wherein capturing comprisescapturing the image projection data at a frame rate in the range of15-30 frames per second.
 49. The machine-readable medium of claim 46,further comprising: generating a treatment plan for the clinicaltreatment machine based on the cone-beam volumetric image data; andusing the treatment plan to instruct the clinical treatment machine toat least adjust a therapeutic radiation source into position to alignthe treatment volume with the therapeutic radiation.
 50. Themachine-readable medium of claim 46, wherein instructing furthercomprises instructing the clinical radiation treatment machine tocapture partial cone image data to reconstruct one of a head size and abody size.
 51. The machine-readable medium of claim 46, furthercomprising instructing a megavoltage radiation source to radiate atarget volume with radiation.
 52. The machine-readable medium of claim46, wherein the clinical radiation treatment machine comprises a drivestand pivotably coupled to the rotatable gantry at a pivotableattachment at which the gantry pivots about an isocenter.
 53. Anapparatus, comprising: a clinical radiation treatment system capable ofimplementing a treatment plan, the system comprising: a frame; arotatable gantry coupled to the frame; a high-energy radiation sourcecoupled to the rotatable gantry to radiate a patient with therapeuticradiation; a cone-beam radiation source coupled to the rotatable gantryto radiate the patient; and a flat-panel imager coupled to the rotatablegantry, wherein the flat-panel imager captures fluoroscopic or cone-beamCT imaging image projection data of the patient from the cone-beamradiation source to generate fluoroscopic or cone-beam computedtomography (CT) volumetric image data of the patient.
 54. The apparatusof claim 53, wherein the flat-panel imager includes an amorphous siliconsensor array capable of fluoroscopic imaging, radiographic imaging, andcone-beam CT imaging.
 55. The apparatus of claim 54, wherein thecone-beam CT radiation source is a kilovoltage radiation source, and theflat-panel imager includes a cesium iodide scintillator for kilovoltageimaging.
 56. The apparatus of claim 55, wherein the scintillatorincludes cesium iodide crystals coated with a reflective powder andepoxy mixture in a large matrix for megavoltage imaging.
 57. Theapparatus of claim 53, further comprising: a treatment plan for theclinical treatment machine based on the cone-beam volumetric image data;and a computing unit, coupled to the rotatable gantry via acommunications network, to store the image projection data captured bythe flat-panel imager, wherein the computing unit generates thetreatment plan based on the image projection data.
 58. The apparatus ofclaim 57, wherein the computing unit generates a three-dimensional imageof a target volume based on the captured image projection data.
 59. Theapparatus of claim 58, wherein the high-energy radiation sourcecomprises: a megavoltage radiation source coupled to the rotatablegantry to radiate the volume with radiation, wherein the megavoltageradiation source comprises a source of between 4 and 25 mega-volts ofradiation.
 60. The apparatus of claim 53, further comprising atranslatable treatment couch coupled to the rotatable gantry via acommunications network, wherein the translatable treatment couch iscapable of movement in three planes plus angulation.
 61. The apparatusof claim 53, wherein the rotatable gantry is capable of 360 degreerotation and the imager is capable of capturing image projection datawhile continuously rotating about a target volume.
 62. The apparatus ofclaim 53, wherein the cone-beam source and high-energy radiation sourceare different from one another, and the cone-beam source comprises a KVsource and wherein the high-energy radiation source comprises a MVsource coupled to the rotatable gantry to radiate a patient withtherapeutic radiation.
 63. An apparatus, comprising: a radiationtreatment simulation system comprising logic configured to determine apatient position relative to a high-energy radiation treatment beam, thelogic comprising at least one of hardwired logic and a programmablecomputer component, the system comprising: a frame; a rotatable gantrypivotably coupled to the frame at a pivot point; a cone-beam imagingradiation source coupled to the rotatable gantry to radiate a patient;and a flat-panel imager coupled to the rotatable gantry, wherein theflat-panel imager is operable to capture image projection data of thepatient to generate cone-beam computed tomography (CT) volumetric imagedata of the patient.
 64. The apparatus of claim 63, wherein theflat-panel imager includes an amorphous silicon sensor array and acesium iodide scintillator, and wherein the imager is capable offluoroscopic imaging, radiographic imaging, and cone-beam CT imaging.65. The apparatus of claim 64, wherein the imager captures fluoroscopicor cone-beam CT imaging kilovoltage image projection data to generatefluoroscopic or cone-beam computed tomography (CT) volumetric image data66. The apparatus of claim 63, further comprising: a computing unit,coupled to the rotatable gantry via a communications network, to storethe image projection data captured by the flat-panel imager and togenerate a three-dimensional image of a target volume based on thecaptured image projection data.
 67. The apparatus of claim 63, whereinthe rotatable gantry is capable of 360 degree rotation and the imager iscapable of capturing image projection data while continuously rotatingabout a target volume.
 68. A method to perform a clinical treatmentsimulation, comprising: rotating a gantry pivotably coupled at a pivotpoint to a frame of a clinical treatment simulator machine comprisinglogic configured to implement a treatment plan for a high-energyradiation treatment beam, the logic comprising at least one of hardwiredlogic and a programmable computer component; irradiating a patient witha radiation source; and using the clinical treatment simulator machineto capture image projection data from a flat-panel imager for generatingcone-beam computed tomography (CT) volumetric image data.
 69. The methodof claim 68, further comprising: generating a treatment plan for aclinical treatment machine based on the cone-beam volumetric image data;transferring the treatment plan to the clinical treatment machine,wherein the clinical treatment machine implements the treatment plan;and using the treatment plan to instruct the clinical treatment machineto at least adjust a therapeutic radiation source into position to aligna treatment volume with the therapeutic radiation.
 70. The method ofclaim 68, wherein the image projection data is generated from theflat-panel imager capturing radiation from a cone-beam computedtomography radiation source passing through a target volume.
 71. Themethod of claim 70, further comprising: continuously rotating theradiation source about the target volume while capturing imageprojection data.
 72. The method of claim 68, wherein rotating furthercomprises pivoting the gantry about an isocenter using a drive standpivotably coupled to the rotatable gantry by a pivotable attachment. 73.The method of claim 68, further comprising: using the flat-panel imagerto capture fluoroscopic, radiographic, and cone-beam CT imaging imageprojection data to generate fluoroscopic, radiographic, and cone-beamcomputed tomography (CT) volumetric image data.
 74. A method to performa clinical treatment simulation, comprising: rotating a gantry pivotablycoupled at a pivot point to a frame of a clinical simulator machinecomprising logic configured to determine a patient position relative toa high-energy radiation treatment beam, the logic comprising at leastone of hardwired logic and a programmable computer component;irradiating a patient with a radiation source; and using the clinicalsimulator machine to capture fluoroscopic or cone-beam CT imaging imageprojection data from a flat-panel imager for generating fluoroscopic orcone-beam computed tomography (CT) volumetric image data.
 75. The methodof claim 74, further comprising: generating a treatment plan for aclinical treatment machine based on the cone-beam volumetric image data;transferring the treatment plan to the clinical treatment machine,wherein the clinical treatment machine implements the treatment plan;and using the treatment plan to instruct the clinical treatment machineto at least adjust a therapeutic radiation source into position to aligna treatment volume with the therapeutic radiation.
 76. The method ofclaim 74, wherein rotating further comprises pivoting the gantry aboutan isocenter using a drive stand pivotably coupled to the rotatablegantry by a pivotable attachment.
 77. The method of claim 74, furthercomprising: using the flat-panel imager to capture fluoroscopic,radiographic, and cone-beam CT imaging image projection data to generatefluoroscopic, radiographic, and cone-beam computed tomography (CT)volumetric image data.